A magnetized graphene oxide modified with 2-mercaptobenzothiazole as a selective nanosorbent for magnetic solid phase extraction of gold(III), palladium(II) and silver(I)

This article describes a useful sorbent for separation and preconcentration of trace amounts of gold(III), palladium(II) and silver(I) ions. Graphene oxide (GO) nanoparticles were synthesized by a modified Hummers method and magnetized by MnFe2O4 nanoparticles to give a sorbent referred to asmag-GO. Addition of sodium dodecyl sulfate creates admicelles on the surface of the mag-GO. Then the metal chelating agent 2-mercaptobenzothiazole (MBT) was immobilized on mag-GO to give a mag-GO-MBT type material. This adsorbent was applied to the preconcentration of gold(III), palladium(II) and silver(I) ions. Following ion desorbed with a solution of thiourea, the ions were quantified by flow injection coupled to ICP-OES. Effect of sample pH value, type and volume of eluent, amount of adsorbent, sample volume, time of adsorption and desorption were optimized. Under optimized condition, the calibration plots are linear in the 2.5 to 25,000 mu g.L-1 concentration range. The limits of detection range from 0.045 to 0.076 mu g.L-1, and enhancement factors are 160, 160 and 140 for gold, palladium and silver ions, respectively. Precisions, expressed as relative standard deviation for 100 mu g.L-1 of each ion are <3.1%. The nanosorbent applied to selective adsorption, extraction and preconcentration of Au(III), Pd(II), and Ag(I) from water, ore and automobile catalyst samples.